1. Field
One or more embodiments relates to an angular velocity sensor.
2. Description of Related Art
Recently, angular velocity sensors have been used in various fields, for example, the military, such as an artificial satellite, a missile, an unmanned aircraft, or the like, vehicles, such as an air bag, electronic stability control (ESC), a black box for a vehicle, or the like, hand shaking prevention of a camcorder, motion sensing of a mobile phone or a game machine, navigation, or the like.
An angular velocity sensor may generally adopt a configuration in which a mass body is adhered to an elastic substrate such as a membrane, or the like, in order to measure an angular velocity through interaction of the mass body and the substrate. Through the configuration, the angular velocity sensor may calculate the angular velocity by measuring a Coriolis force applied to the mass body.
In detail, a scheme of measuring the angular velocity using the angular velocity sensor is as follows. First, the angular velocity may be measured based on the Coriolis force “F=2mΩv”, where “F” represents the Coriolis force acting on the mass body, “m” represents the mass of the mass body, “Ω” represents the angular velocity to be measured, and “v” represents the motion velocity of the mass body. Among others, since the motion velocity v of the mass body and the mass m of the mass body may be values known in advance, the angular velocity Ω may be derived by detecting the Coriolis force (F) acting on the mass body.
Accordingly, in an example where the angular velocity sensor includes a piezoelectric material disposed on a membrane (a diaphragm) in order to drive a mass body or sense displacement of the mass body adhered to the membrane, the angular velocity. It may be desirable to allow a resonant frequency of the corresponding driving mode and a resonant frequency of the corresponding sensing mode to substantially coincide with each other.